Abstract: A tamperproof container and cap assembly in which the container carries a circumferential radially extending flange which cooperates with the skirt of the cap to prevent the cap from being removed until a portion of the cap skirt is removed. The cap skirt has a circumferential frangible section formed by an internal groove. A pair of spaced lugs are carried by the skirt and a frangible membrane couples the spaced lugs to the frangible section and to each other. The lugs are spaced a sufficient distance to permit the insertion of a tool which may be operated to force the lugs apart thereby breaking the frangible membrane, with one of the lugs forming a pull tab. The pull tab is operative when pulled to cause removal of a portion of the cap skirt, thereby allowing access to the cap for removal.